Most organic fertilizers provide everything the plant needs. You could fine tune it I suppose but I definitely don't.

Morpheuspa is an advocate of winterizing the lawn at the end of fall. The end of fall is defined as that moment when you notice the grass has stopped growing but is not dormant yet. In Florida that day may never come if you continue fertilizing and watering weekly. I know in San Antonio it is a rare (cold) winter when we cannot maintain a St Augustine lawn all through the year. Most people choose to let it go dormant, but you don't have to. I would think in FL it would be a very rare time. If you want to winterize, use a fast release fertilizer that is heavy on the N value and much lighter on the other values. I believe he uses an uncoated urea product.

If you are mowing at your mower's highest setting, the bermuda should be fading out. It does not like to compete with the tall, coarse, St Augustine blades.